A rotary evaporator is a laboratory apparatus which typically comprises a heating bath and an evaporator flask which can dip into the heating bath. In operation, a liquid medium present in the heating bath, for example water or—for higher temperatures—oil, is heated in order thus to heat the evaporator flask dipped into the heating bath. A mixture, in particular a liquid mixture, contained in the evaporator flask can hereby be heated so that the respective distillate, in particular solvent, is evaporated. The evaporated distillate then flows into a cooler of the rotary evaporator to condense there. The condensate is subsequently collected in a collection flask. The distillation residue remaining in the evaporator flask can be further processed or analyzed. A vacuum pump is frequently additionally provided for the generation of a vacuum in the evaporator flask and in the cooler to lower the boiling point, whereby the distillation can be accelerated and the distillation rate can be increased. A heating bath is, however, not absolutely necessary. An evaporation can, for example, also be effected solely by generating a vacuum. A heating dish, a heating mantle or a heating quiver can e.g. also be used instead of a heating bath.
A rotary evaporator furthermore comprises a rotary drive to rotate the evaporator flask in the heating bath or in the respective heating medium. The evaporator flask is uniformly heated due to the rotation and a thin liquid film is produced at the heated inner wall of the evaporator flask which has a large surface and from which the distillate can be evaporated fast, efficiently and gently.
It is known to couple the evaporator flask to the rotary drive of the rotary evaporator using a kind of retainer nut or using a clamping mechanism. The coupling or fastening of above all large evaporator flasks, in particular then they are filled, however, often presents the user with difficulties since it is necessary for the respective fastening to position the flask neck of the evaporator flask sufficiently exactly at the rotary drive to be able to actuate the respective fastening mechanism. The release of the evaporator flask is occasionally also correspondingly difficult.